In a wide area network (WAN)/cellular scenario, communications between mobile devices are via the uplink/downlink channels between mobiles and base stations. In such a case, communication between mobiles is routed through a base station. In the case that two communicating mobiles are in the vicinity of each other, direct peer to peer communication without going through a base station may be possible and has the potential to reduce base station loading.
Typical WAN deployments are in one of two modes, FDD (Frequency Division Duplexing) in which different frequency bands are used for uplink and downlink communications and TDD (Time Division Duplexing) in which the same frequency band is used for uplink and downlink communications but at different times. Due to implementation issues, FDD is the preferred method of deployment in many situations, particularly cellular systems, since the devices in FDD spectrum do not have to switch between transmitting and receiving in the same spectrum.
In contrast to WAN/Cellular communications, peer to peer communication is typically short distance and is not usually power limited. Additionally, since peer to peer communication tends, by its nature, to be symmetrical, peer to peer communications is well suited for TDD methods of communication.
In view of the above discussion, it should be appreciated that it would be desirable if methods and apparatus could be developed which would allow devices to perform WAN communications using FDD but peer to peer traffic communications using TDD signaling.